//更新总的未读消息数量，显示到tab上
function updateChattingTabNoReadCount(count) {
    if (count <= 0) {
        taskTabPanel.down('#chatTab').setTitle('聊天窗口');
        taskTabPanel.down('#chatTab').setIcon('static/images/icons/fam/noTip.ico');
    } else {
        taskTabPanel.down('#chatTab').setTitle('聊天窗口(未读:' + count + '条)');
        taskTabPanel.down('#chatTab').setIcon('static/images/icons/fam/tip.ico');
    }
}